Note: Descriptions are shown in the official language in which they were submitted.
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M D-02-25-PO
RIGID FOAMS AND A PROCESS
FOR THE PRODUCTION OF SUCH FOAMS
FIELD OF THE INVENTION
The present invention relates to a process for producing rigid foams
with good insulation characteristics (as measured by k-factor) and to the
foams produced by this process. The present invention also relates to
blowing agents useful in producing foams with good insulation
characteristics.
BACKGROUND OF THE INVENTION
Rigid polyurethane foams and processes for their production are
known. Such foams are typically produced by reacting an isocyanate with
an isocyanate-reactive compound such as a polyol in the presence of a
blowing agent. Chlorofluorocarbons were the blowing agents most
~ commonly used until about 1996. However, when it became known that
chlorofluorocarbons posed environmental problems, specifically the
depletion of ozone in the earth's atmosphere, the search for alternative
blowing agents began.
Among the blowing agents considered to be promising alternatives
to the chlorofluorocarbons (CFCs) were the hydrogen-containing
chlorofluorocarbons (HCFCs), hydrogen-containing fluorocarbons (HFCs),
hydrocarbons, and mixtures of HCFCs and HFCs. HCFC-141 b was one of
the most promising replacements for CFCs as a blowing agent for rigid
foams, however it is currently in the process of being eliminated as an
environmentally acceptable blowing agent. One of the most promising
replacements for HCFC-141 b in many applications is HFC 245fa, which
produces foams with properties very similar to those of foams produced
with HCFC-141 b in terms of both density and average k-factor at
appliance operating temperatures. However, HFC 245fa is high in both
cost and molecular weight, and more HFC 245fa is required to produce
foams with properties similar to foam produced with HCFC-141 b.
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U.S. Patent Nos. 5,889,006 and 5,840,212, disclose rigid foams
made with a blowing agent mixture composed of from about 1 to about
30% by weight of at least one C2-C5 polyfluoroalkane and from about 70 to
about 99% by weight of a liquid HCFC. These references disclose that
levels of C2-C~ polyfluoroalkane above 30% by weight of the total blowing
agent mixture have a detrimental effect upon thermal conductivity
properties of the resultant foam.
U.S. Patent N~. 5,565,497 discloses a process for the production of
filled rigid polymer foams in which a fluorochemical surFactant and a
blowing agent that is a hydrogen containing halocarbon or a mixture of
hydrogen containing halocarbons are used.
U.S. Patent No. 5,397,808 discloses low thermal conductivity foams
made with a combination of HCFC-141 b, perfluorinated compounds and
carbon black. The perfluorinated compounds taught to be useful in this
blowing agent combination include perfluorinated aliphatic hydrocarbons,
perfluorinated cycloaliphatic hydrocarbons, perfluorinated N-aliphatic
amino ethers, cyclic amino ethers, 1,3- or 1,4-amino ethers, perfluorinated
ethers and perfluorinated tertiary aikylamines.
U.S. Patent No. 5,318,996 discloses rigid insulating polyurethane
foams prepared from ternary blowing agent mixtures which blowing agent
mixtures were composed of water, HCFC-22 or HCFC-141 b and a
perfluorinated hydrocarbon having from 3 to 8 carbon atoms.
U.S. Patent Nos. 4,927,863 and 4,945,119 disclose a process for
the production of closed-cell polyurethane foams in whicll a mixture of a
2 carbon hydrogen-containing halocarbon (such as HCFC-141 b and
HCFC-123) with a shrinkage-minimizing halocarbon such as any of the
known CFCs, HCFC-22, HFC-32, HCFC-124, HCFC-133a, HFC-134a,
HCFC-142b and HFC-152a is used as the blowing agent.
U.S. Patent No. 4,960,804 discloses rigid foams produced using a
blend of a chlorofluorocarbon and an alkyl alkanoate as the blowing agent.
HCFC's such as 1,1-dichloro-2,2,2-trifluoroethane (HCFC 123) and
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1,1-dichloro-1-fluoroethane (HCFC 141 b) are among the chlorofluoro-
carbons taught to be suitable.
U.S. No. 4,996,242 discloses polyurethane foams made with two
different halocarbons and an inert organic liquid are combined in specified
amounts to form a ternary mixture which mixture is used as the blowing
agent. The halocarbons taught to be suitable blowing agents for the
disclosed ternary mixtures include at least one halocarbon having a boiling
point below about 10°C and at least one halocarbon having a boiling
point
from about 20 to about 35°C. Halocarbons having boiling points below
10°C include 1,1-difluoroethane, 1-chloro-1,1-difluoroethane, 1-chloro-
1,1,2,2,-tetrafluoroethane, 1-chloro-1,1,1,2-tetrafluoroethane and mixtures
thereof. Halocarbons having a boiling point from 20 to 35°C include
trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane and 1,1-dichloro-
1-fluoroethane. The inert organic liquids which are included in these
ternary mixtures include pentane and substituted pentanes, hexane and
b
substituted hexanes and haioalkanes.
U.S. Patent No. 5,057,547 discloses mixtures of specific
hydrochlorofluorocarbons and specific hydrocarbons, which are useful in
the production of rigid, closed cell foams. The HCFC's useful in these
disclosed mixtures include 2,2-dichloro-1,1,1-trifluoroethane and
1,1-dichloro-1-fluoroethane. The hydrocarbons useful in these mixtures
include n-pentane, 2-methyl butane, hexane, the position isomers of
hexane and mixtures thereof.
U.S. Patent No. 5,162,384 discloses foamed plastics made with
blowing agent emulsions composed of at least one low boiling
perfluorinated, N-aliphatic, cyclic 1,3- or 1,4- aminoether blowing agent, a
foamable reaction mixture and a fluorochemical surfactant.
U.S. Patent Nos. 5,254,601 and 5,272,183 each discloses
HCFC-blown rigid foams having low thermal conductivities. These foams
are produced using a blowing agent mixture that includes from about 0.1
to about 1.0% by weight water and 1,1-dichloro-2,2,2-trifluoroethane or
dichlorofluoroethane.
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U.S. Patent No. 5,314,926 discloses foams blown with mixtures of
1,1,1,2,3,3,3-heptafluoropropane and one or more hydrocarbons or
partially halogenated alkanes.
U.S. Patent No. 5,470,891 discloses rigid polyisocyanate-based
foams which are produced using water and a C1~. hydrofluorocarbon
having a boiling point of 300°K or less as the blowing agent.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process for the
production of rigid foams having good insulation properties.
It is also an object of the present invention to provide a blowing
agent mixture for use in the production of rigid polyurethane foams which
does not include a CFC.
It is another object of the present invention to provide rigid foams
having low thermal conductivities, which are produced in the absence of
HCFC-141 b.
These and other objects which will be apparent to those skilled in
the art are accomplished by reacting an organic isocyanate with an
isocyanate-reactive compound in the presence of a blowing agent mixture
made up of from 1 to 70°/~ by weight of a gaseous hydrogen containing
chlorofluorocarbon and from 30 to 99% by weight of a C2-C5 hydrogen-
containing fluorocarbon.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
The present invention relates to a blowing agent mixture, to rigid
foams having low thermal conductivities as measured by k-factor (i.e., a
thermal conductivity wfrich are similar to or lower than the thermal
conductivity of a rigid foam produced using a single hydrochlorofluoro-
carbon, a single hydrofluorocarbon or a mixture of hydrofluorocarbons as a
blowing agent) and to a process for the production of those foams in which
no CFC or HCFC-141 b are used as the blowing agent. Preferably, the
present invention relates to rigid foams having thermal conductivities in the
range of 0.130 to 0.136 BTU-in./hr.ftz°F at 75°F.
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The blowing agent mixture of the present invention is made up of
from 1 to 70% by weight of a low boiling (b.p. < 0°C), hydrogen
containing
chlorofluorocarbon and from 30 to 99% by weight of a C~-C~
polyfluoroalkane.
Suitable gaseous 1-ICFC's include chlorodifluoromethane (HCFC-22),
1-chloro-1,1-difluoroethane (HCFC-142b) and mixtures thereof. Preferably
the HCFC is chlorodifluoromethane (HCFC-22).
Suitable C2-C5 polyfluoroalkanes include 1,1,1,3,3-pentafluoropropane
(HFC-245fa), 1,1,1,2,3,3-hexafluoropropane (NFC-236ea), 1,1,1,3,3,3-
hexafluropropane (HFC-236fa), 1,1,1,3,3-pentafluorobutane (HFC-365mfc),
and 1,1,1,4,4,4-hexafluorobutane (HFC-356mffm). Preferably, the C2-C~
polyfluoroalkane is 1,1,1,3,3-pentafluoropropane (~fFC-245fa).
Preferably, the blowing agent contains from about 20 to 50% by
weight of a hydrogen containing chlorofluorocarbon and from 50 to 80
°/~
by weight of a C2-C5 polyfluoroalkane.
lNater may optionally be included in the blowing agent mixture of
the present invention. If used, water is generally included in an amount of
up to 2.0 weight percent, based on the total weight of the polyol blend.
As is known in the art, rigid foams are prepared by reacting
polyisocyanates with isocyanate-reactive compounds. Any of the known
organic polyisocyanates may be used in the present invention. Suitable
polyisocyanates include aromatic, aliphatic and cycioaliphatic poly-
isocyanates and combinations thereof. Representative of these types are
diisocyanates such as m-phenylene diisocyanate, p-phenylene
diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate,
1,6-hexamethylene diisocyanate, 1,4-hexamethylene diisocyanate,
1,4-cyclohexane diisocyanate, the isomers of hexahydrotoluene
diisocyanate, 1,5-naphthylene diisocyanate, 1-methylphenyl-2,4-phenyl
diisocyanate, 4,4°-diphenylmethane diisocyanate, 2,4°-
diphenylmethane
diisocyanate, 4,4°-biphenylene diisocyanate, 3,3'-dimethoxy-4,4°-
biphenylene diisocyanate, and 3,3'-dimethyldiphenylpropane-4,4'-
diisocyanate; triisocyanates such as 2,4,6-toluene triisocyanate; and
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polyisocyanates such as 4,4'-dimethyl-diphenylmethane-2,2',5,5'-
tetraisocyanate and the p~lymethylene polyphenylisocyanates.
A crude polyisocyanate may also be used in making polyurethanes,
such as the crude toluene diisocyanate obtained by the phosgenation of a
mixture of toluene diamines. Preferred undistilled or crude toluene
polyisocyanates are disclosed in J.S. Patent 3,215,552. Similarly,
undistilled polyisocyantates, such as methylene bridged
polyphenylpolyisocyanates are useful in the present invention and are
obtained by the phosgenation of polyphenylpolymethylenepolyamines
obtained by the known process of the condensation of aromatic amines
such as aniline with formaldehyde.
Suitable modified diisocyanates or polyisocyanates may be
obtained by chemical reaction of diisocyanates andlor polyisocyanates.
Modified isocyanates useful in the practice of the present invention include
isocyanates containing ester groups, urea groups, biuret groups,
allophanate groups, carbodiimide groups, isocyanurate groups, uretdione
groups andlor urethane groups.
More preferred polyisocyanates for making rigid polyurethanes are
methylene-bridged polyphenyl poiyisocyanates and prepolymers of
methylene-bridged polyphenyl polyisocyanates, having an average
functionality of from about 2.0 to about 3.5, preferably about 2.1 to about
3.1 isocyanate moieties per molecule and an NC(~ content of from about
28 to about 34.% by weight, due to their ability to cross-link the
polyurethane. The isocyanate index (ratio of equivalents of isocyanates to
equivalents of active hydrogen-containing groups) is advantageously from
about 0.9 to about 3.0, preferably about 1.0 to about 2.0 and most
preferably from about 1.0 to about 1.5.
Any of the known polyfunctional isocyanate reactive organic
compounds may be used to produce foams in accordance with the present
invention. The reactive compound can be a single polyol or blend of 2 or
more polyols selected so that the polyol or polyol blend has an average of
at least three isocyanate-reactive hydrogen atoms per molecule and a
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hydroxyl (OH) number of from about 200 to about 800, preferably from
about 300 to about 650. When a blend of polyols is used, the individual
polyols making up the blend can have hydroxyl numbers and
functionalities that fall outside the preferred range of the blend.
The molecular weight of the isocyanate-reactive materials are
determined from the functionality of the polyol(s) and the equivalent weight
determined by the end group analysis method generally used by those
skilled in the art and represent a number average molecular weight.
Suitable poiyols may be prepared by reacting one or more suitable
initiators containing active hydrogens with alkylene oxide. Suitable
initiators are those containing at feast 2 active hydrogens or combinations
of initiators where the mole average of active hydrogens is at leas at 3,
preferably from about 3 to about 7, and more preferably from about 3.5 to
about 6. Active hydrogens are defined as those hydrogens which are
observed in the well-known Zerewitinoff test, see I~Cohler, Journal of the
American Chemical Society, p. 3'181, Vol. 49 (1927). Representative of
such active hydrogen-containing groups include -OH, -COOH, -SH and
NHR where R is H or alkyl, aryl aromatic group and the like.
Examples of suitable initiators include pentaerythritol, carbohydrate
compounds such as lactose, a-methylglucoside, oc-hydroxyethyl-glucoside,
hexitol, heptitol, sorbitol, dextrose, mannitol, sucrose and the like.
Examples of suitable aromatic initiators containing at least four active
hydrogens include aromatic amines such as toluene diamine, preferably,
ortho-toluene diamine and methane diphenylamine, the reaction product of
a phenol with formaldehyde, and the reaction product of a phenol with
formaldehyde and a dialkanolamine such as described by tJ.S. Patent
Nos. 3,297,597; 4,137,265 and 4,383,102 (incorporated herein by
reference). Other suitable initiators which may be used in combination
with the initiators containing at least four active hydrogetls include water,
glycols, glycerine, trimethylolpropane, hexane triol, aminoethyl piperazine
and the like. These initiators contain less than four active hydrogens and
therefore can only be employed in quantities such that the total mole
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average of active hydrogens per molecule remains at least about 3Ø
More preferred initiators for the preparation of the high functionality, high
molecular weight polyols comprise sucrose, dextrose, sorbitof, cc-methyl-
glucoside, a-hydroxy-ethylglucoside and toluene diamine that may be
employed separately or in combination with other initiators such as
glycerine, propylene glycol, or water.
The polyols may be prepared by methods well known in the art
such as taught by Wurtz, The Encyclopaedia of Chemical Technoloqy_,
Vol. 7, p. 257-266, lnterscience Publishers Inc. (1951 ) and U.S. Patent
1,922,459. For example polyether polyols can be prepared by reacting, in
the presence of an oxyalkylation catalyst, the initiator with an alkylene
oxide. A wide variety of oxyalkylation catalysts may be employed, if
desired, to promote the reaction between the initiator and the alkylene
oxide. Suitable catalysts include those described in U.S. Patents
3,393,243 and 4,595,743, incorporated herein by reference. However, it is
preferred to use as a catalyst a basic compound such as an alkali metal
hydroxide, e.g., sodium or potassium hydroxide, or a tertiary amine such
as trimethylamine. The reaction is usually carried out at a temperature of
about 60°C to about 160°C, and is allowed to proceed using such
a
proportion of aikylene oxide to initiator so as to obtain a polyol having a
hydroxyl number ranging from about 200 to about 800, preferably about
300 to about 650, most preferably from about 350 to about 500. The
hydroxyl number range of from about 200 to about 800 corresponds to an
equivalent weight range of about 280 to about 70.
Polyols of a hydroxyl number greater than 800 may be used as
optional ingredients in the process of the present invention.
The alkylene oxides which may be used in the preparation of the
polyol include a,(3-oxiranes, cyclic ethers having a three member ring, and
are unsubstituted or alternatively substituted with inerfi groups which do not
chemically react under the conditions encountered while preparing a
polyol. Examples of suitable alkyiene oxides include ethylene oxide,
propylene oxide, 1,2- or 2,3-butylene oxide, the various isomers of hexane
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oxide, styrene oxide, epichlorohydrin, epoxychlorohexane,
epoxychloropentane and the like. Most preferred, on the basis of
performance, availability and cost are ethylene oxide, propylene oxide,
butylene oxide and mixtures thereof, with ethylene oxide, propylene oxide,
or mixtures thereof being most preferred. When polyols are prepared with
combinations of alkylene oxides, the alkylene oxides may be reacted
together, as a mixture providing a random distribution of oxyalkylene units
within the oxide chain of the polyol or alternatively they may be reacted in
a step-wise manner so as to provide a block distribution within the
oxyalkylene chain of the polyol.
The amines and polyamines useful as starters in the practice of the
present invention may be prepared by any of the known methods. For
example, via the nitration of an aromatic hydrocarbon with nitric acid
followed by reduction, as in the preparation of toluene diamine (TDA), or
via the reaction of ammonia with epoxides to obtain alkanol amines, such
as ethanol amine, or via the condensation reaction of aldehydes with
aromatic amines such a aniline to produce methylene bridged
polyphenylpolyamines (polymeric methylene dianiline, otherwise known as
MDA). Suitable optional polyols include polyether polyols, polyester
polyols, polyhydroxy-terminated acetai resins, hydroxy-terminated amines
and polyamines. Examples of these and other suitable materials are
described more fully in U.S. Patent 4,394,491, particularly in columns 3 to
5 thereof. Most preferred for preparing rigid foams are those having from
about 2 to about 7 active hydrogens and having a hydroxyl number from
about 50 to about 800, preferably from about 100 to about 650. Examples
of such polyols include those commercially available under the product
names Terate (available from KoSa), Stepanpol (available from Stepan
Chemical Corporation) and Multranol (available from Sayer Corporation).
~ther components useful in producing the poiyurethanes of the
present invention include catalysts, surfactants, pigments, colorants,
fillers,
antioxidants, flame retardants, stabilizers, and the like.
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When preparing polyisocyanate-based foams, it is generally
advantageous to employ a minor amount of a surfactant to stabilize the
foaming reaction mixture until it obtains rigidity. Such surfactants
advantageously comprise a liquid or solid organosilicon compound. Other,
less preferred surfactants include polyethylene glycol ethers of long chain
alcohols, tertiary amine or alkanolamine salts of long chain alkyl acid
sulfate esters, alkylsuifonic esters and alkyiarylsulfonic acids. Such
surfactants are employed in amounts sufficient to stabilize the foaming
reaction mixture against collapse and the formation of large and uneven
cells. Typically, about 0.2 to about 5.0 parts by weight of the surfactant per
100 parts polyol composition are sufficient for this purpose.
One or more catalysts are advantageously used. Any suitable
urethane catalyst may be used including the known tertiary amine
compounds and organometallic compounds. Examples of suitable tertiary
amine catalysts include triethylenediamine, N-methylmorpholine,
pentamethyl diethylenetriamine, dimethylcyclohexylamine, tetramethyl-
ethylenediamine, 1-methyl-4-dimethylaminoethyl-piperazine,
3-methoxy-N-dimethyi-propylamine, N-ethylmorpholine, diethylethanol-
amine, N-cocomorpholine, N,N-dimethyl-N°,N°-dimethylisopropyl-
propylene
diamine, N,N-diethyl-3-diethyl aminopropylamine and dimethyl-benzyl
amine. Examples of suitable organometallic catalysts include
organomercury, organolead, organoferric and organotin catalysts, with
organotin catalysts being preferred. Suitable organotin catalysts include
tin salts of carboxylic acids such as dibutyltin di-2-ethyl hexanoate and
dibutyltin dilaurate. Metal salts such as stannous chloride can also
function as catalysts for the urethane reaction. A catalyst for the
trimerization of polyisocyanates, such as an alkali metal alkoxide or
carboxylate, or certain tertiary amines may also optionally be employed
herein. Such catalysts are used in an amount, which measurably
increases the rate of reaction of the polyisocyanate. Typical amounts are
about 0.01 to about 3 part of trimerization catalyst per 100 parts by weight
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of polyoi. Examples of such catalysts include the potassium salts of
carboxylic acids such as potassium octoate, and the tertiary amine
N,N',N"-tris(3-dimethyiaminopropyl) hexahydro-s-triazine,
The components described may be employed to produce rigid
polyurethane and polyurethane-modified isocyanurate foam. The rigid
foams of the present invention may be made in a one-step process by
reacting all of the ingredients together at once, or foams can be made by
the so-called "quasi prepoiymer" method. In the one-shot process where
foaming is carried out using machines, the active hydrogen containing
compounds, catalyst, surfactants, blowing agents and optional additives
may be introduced separately to the mixing head where they are combined
with the poiyisocyanate to give the polyurethane-forming mixture. The
mixture may be poured or injected into a suitable container or molded as
required. For use of machines with a limited number of component lines
infio the mixing head, a premix of all the components except the
polyisocyanate can be advantageously employed. This simplifies the
metering and mixing of the reacting components at the time the
polyurethane-forming mixture is prepared.
Alternatively, the foams may be prepared by the so-called '°quasi
prepoiymer" method. in this method a portion of the polyol component is
reacted in the absence of catalysts with the polyisocyanate component in
proportion so as to react from about 10 percent to about 30 percent of free
isocyanate groups based on the polyisocyanate. To prepare foam, the
remaining portion of the polyol is added and the components are allowed
to react together in the presence of catalysts and other appropriate
additives such as blowing agent, surfactant, etc. Other additives may be
added to either the isocyanate prepolymer or remaining polyol or both prior
to the mixing of the components, whereby at the end of the reaction a rigid
polyurethane foam is provided.
The polyurethane foams of this invention are useful in a wide range
of applications. Accordingly, not only can rigid appliance insulating foam
be prepared buff also spray insulation, rigid insulating board stock,
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laminates and many other types of rigid foam can easily be prepared
according to this invention.
The following Examples are given as being illustrative thereof. All
parts and percentages given in these Examples acre parts by weight and
percentages by weight, unless otherwise indicated.
EXAMPLES
The following materials were used in the Examples, which follow:
POLYOL: A blend made up of (1 ) 55% by weight (based on total
weight of POLYOL blend) of an polyether polyol
prepared by alhoxylating a sucrose" propylene glycol
and water starter having a hydroxyl number of about
470 mg KOHIg and a functionality of about 5.2;
(2) 25% by weight (based on total weight of POLYOL
blend) of an ortho-toluene diamine-initiated polyether
polyol having a hydroxyl number of about 390 mg
KOHIg and a functionality of about 4; and (3) 20% by
weight (based on total weight of POLYOL blend) of
Stepanpol PS-2502A, an aromatic polyester polyol
having an OH number of about 240 mg KOHIg which
is commercially available from Stepan Company.
SURFACTANT: A silicone surfactant that is commercially available
from Air Products and Chemicals Inc. under the
designation DABCO DC-535'x.
CATALYST A: (Pentamethyldiethylenetriamine) A tertiary amine
catalyst that is commercially available from Rhein
Chemie Corporation under the name Desmorapid PV.
CATALYST B: A strongly basic, amber-brown liquid having a
characteristic amine odor which is commercially
available from Air Products under the designation
Polycat 41.
HCFC-22: Chlorodifluoromethane, commercially available from
DuPont under the designation Formacel S.
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HFC-245fa: 1,1,1,3,3-pentafluoropropane, commercial 1y available
from Honeywell under the designation Enovate 3000.
ISO: A modified polymeric methylenediphenyl diisocyanate
having an NCO group content of about 30.5% which is
available from Bayer Corporation as IVDondur 1515.
EXAIV1PLES 1 AND 2
POLYOL, SURFACTANT, CATALYST A, CATALYST B, WATER
and the blowing agents HCFC 22 and HFC 245fa were combined in the
amounts indicated in TABLE 1. This mixture was then combined with the
amount of ISO indicated in TABLE 1. All foams were prepared using an
NK-100 high pressure Fiennecke foam machine with an UIQ 12-2 mixhead.
The liquid output was maintained at a constant 60 Ibslmin. and the recycle
and pour pressures were held at 1500 psig. The minimum fill density was
determined from foam panels poured into a temperature controlled Bosch
Panel mold at 120 °F (49 °C) with an internal volume of 79
inches
(200 cm) by 8 inches (20 cm) by 2 inches (5 cm). The liquid foam mixture
was injected into the mold through the pour hole located near the bottom
while the mold was held in a vertical position. The minimum fill density
was determined from the minimum weight of foam that was needed to just
f(1 the mold's interior volume. To do this, three panels were poured at
about 55, 65, and 75 inches (140, 165, and 190 cm) and linear regression
of weight versus height was used to determine the minimum fill weight and
calculate the minimum fill density. Panels were then prepared at four
higher densities of about 0.10, 0.15, 0.20 and 0.25 Iblft3 over the minimum
fill density. The top half of each panel was cut into ten sections of about
4 inches (10 cm ) each and subjected to -4 °F (-20 ° C) for at
least 16 hours.
The panel with the lowest density which exhibited no significant dimensional
change was considered to be freeze stable. Additional panels for foam
properties were all prepared at this "freeze stable density". The properties
of
the foam are reported in TABLE 1.
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TABLE 1:
* I 2
POLYOL pbw 66.72 71.1
SURFACTANT pbw 2.42 2.47
CATALYST A, bw 1.33 ~ 1.33
'' CATALYST B pbw 0.66 0.66
i WATER bw 0.30 0.82
HCFC-22 pbw -- 9.26
HFC-245fa pbw ~ 28.07 14.35
~
'~~ ; 93.4 97.9
ISO bw
Minimum fill weight Iblft'~1.89 2.07
Freeze Stable Densit , 2.09 2.22
Iblft 35F 0.116 0.114
Avera a k-Factor Btu-inl
hr.ft2F
Avera a k-Factor Btu-in./ 75F ' 0.131 ! 0.130
hr.ft F
~ Averacte Core Density 1.93 ~ 2.03
~Ibs/ft )
* Comparative Example
Although the invention has been described in detail in the foregoing
for the purpose of illustration, it is to be understood that such detail is
solely for that purpose and that variations can be made therein by those
skilled in the art without departing from the spirit end scope of the
invention except as it may be limited by the claims.
